Increased genetic divergence between two closely related fir species in areas of range overlap

Because of introgressive hybridization, closely related species can be more similar to each other in areas of range overlap (parapatry or sympatry) than in areas where they are geographically isolated from each other (allopatry). Here, we report the reverse situation based on nuclear genetic divergence between two fir species, Abies chensiensis and Abies fargesii, in China, at sites where they are parapatric relative to where they are allopatric. We examined genetic divergence across 126 amplified fragment length polymorphism (AFLP) markers in a set of 172 individuals sampled from both allopatric and parapatric populations of the two species. Our analyses demonstrated that AFLP divergence was much greater between the species when comparisons were made between parapatric populations than between allopatric populations. We suggest that selection in parapatry may have largely contributed to this increased divergence.     

Chloroplast diversity and population differentiation of Castanopsis fargesii (Fagaceae): a dominant tree species in evergreen broad-leaved forest of subtropical China

Subtropical forests in China constitute the major expanse of evergreen broad-leaved forest in East Asia. The significant genetic divergence of the keystone tree species should be expected due to the huge geomorphological and environmental changes from west to east in subtropical China. In this study, a total of 652 individuals from 27 populations of Castanopsis fargesii throughout its natural range in mainland China were genotyped with eight chloroplast microsatellite markers to investigate genetic diversity, population differentiation, and demographic history of C. fargesii. Phylogeographic structure among populations of C. fargesii was evidenced by the permutation test, revealing that N_ST was significantly higher than G_ST . The strong genetic differentiation found among populations was well in accordance with isolation-by-distance model. In addition, significant isolation by elevation was detected among populations. Significant genetic differentiations were revealed among the west, center, and east regions by approximate Bayesian computations (ABC). The genetic divergence might reflect the regional responses to the fast and dramatic uplift of Yunnan-Guizhou Plateau and Wuyi mountain range in the Pleistocene. In the present study, contraction-expansion process was detected in the west, center, and east regions, indicating that geomorphological remodeling together with climatic changes in the Pleistocene had strong impact on genetic structure of C. fargesii.     

Allozyme,chloroplast DNA and RAPD markers for determining genetic relationships between Abies alba and the relic population of Abies nebrodensis

Allozyme, chloroplast (cpDNA) and random amplified polymorphic DNA (RAPD) markers have been used to estimate genetic and taxonomic relationships among different populations of Abies alba and the relic population of A. nebrodensis. Twelve isozyme gene loci, as well as restriction fragment length polymorphism (RFLP) at cpDNA spacer regions between t-RNA genes were analysed. Moreover, a set of 60 random sequence 10-mer primers were tested. Over all isozyme loci, evident differences in allele frequencies among A. nebrodensis and A. alba populations were found, particularly at 2 loci, phosphoglucose isomerase (Pgi-a) and shikimate dehydrogenase (Skd-a). More than 10% of the total genetic diversity was due to differences among populations. High values of genetic distances among populations were also found. Out of the 60 primers tested, 12 resulted in a polymorphic banding pattern both within and among populations. A total of 84 RAPD fragments were produced by the 12 selected primers. A phenogram of relationships among populations was constructed based on RAPD band sharing: the differentiation of the A. nebrodensis population was evident. The analysis of molecular variance (AMOVA) was used to apportion the variation among individuals within populations and among populations. There was considerable variation within each population: even so, genetic divergence was found among populations. This pattern of genetic variation was very different from that reported for inbred species. Identical cpDNA amplification and restriction patterns were observed among all the individuals sampled from the populations. Taken together, the results of allozyme and RAPDs show a clear differentiation among A. nebrodensis and A. alba populations and provide support for their classification into two different taxonomic groups.     

Genetic variation in Tertiary relics: The case of eastern‐Mediterranean Abies (Pinaceae)

The eastern‐Mediterranean Abies taxa, which include both widely distributed species and taxa with minuscule ranges, represent a good model to study the impacts of range size and fragmentation on the levels of genetic diversity and differentiation. To assess the patterns of genetic diversity and phylogenetic relationships among eastern‐Mediterranean Abies taxa, genetic variation was assessed by eight nuclear microsatellite loci in 52 populations of Abies taxa with a focus on those distributed in Turkey and the Caucasus. Both at the population and the taxon level, the subspecies or regional populations of Abies nordmanniana s.l. exhibited generally higher allelic richness, private allelic richness, and expected heterozygosity compared with Abies cilicica s.l. Results of both the Structure analysis and distance‐based approaches showed a strong differentiation of the two A. cilicica subspecies from the rest as well as from each other, whereas the subspecies of A. nordmanniana were distinct but less differentiated. ABC simulations were run for a set of scenarios of phylogeny and past demographic changes. For A. ×olcayana, the simulation gave a poor support for the hypothesis of being a taxon resulting from a past hybridization, the same is true for Abies equi‐trojani: both they represent evolutionary branches of Abies bornmuelleriana.     

Genetic assessment of <Emphasis Type="Italic">Abies koreana</Emphasis> (Pinaceae), the endangered Korean fir,and conservation implications

To establish a management plan for endangered and rare species, genetic assessment must first be conducted. The genetic characteristics of plant species are affected by demographic history, reproductive strategy, and distributional range as well as anthropological effects. Abies koreana E. H. Wilson (Pinaceae), Korean fir, is endemic to Korea and found only in sub-alpine areas of the southern Korean Peninsula and Jejudo Island. This species has been designated as critically endangered by the International Union for Conservation of Nature due to a continuous decline in its range and population fragmentation. We genotyped 176 individuals from seven natural populations and two afforested populations on the Korean Peninsula using 19 microsatellite loci. STRUCTURE analysis revealed two genetic clusters in natural populations (F _st  = 0.040 and R _st  = 0.040) despite low differentiation. We did not detect a significant reduction in genetic diversity or the signature of a genetic bottleneck despite population fragmentation and small population size. We deduced that this species exhibits a metapopulation structure, with the population on Jirisan Mountain acting as a source of genetic diversity for other local small populations on the Korean Peninsula, through contemporary asymmetric gene flow. However, the majority of afforested individuals on the Korean Peninsula originated from a different gene cluster. Thus, we recommend a conservation strategy that maintains two genetically unique clusters.     

Assessment of genetic diversity and population differentiation of Achyranthes bidentata (Amaranthaceae) in Dao Di and its surrounding region based on microsatellite markers

Identifying genetic diversity patterns is fundamentally important for effective species management and conservation. In this study, we used five microsatellite loci to investigate the genetic diversity and population differentiation of Achyranthes bidentata in Dao Di and its surrounding region. Our analysis of microsatellite data indicated the level of genetic diversity of A. bidentata (H_T = 0.333) was lower than other plants. The results showed no significant genetic diversity differences and population genetic differentiation between the Dao Di and surrounding region. Significant temperature differences (Bio2: mean diurnal range and Bio7: temperature annual range) were found between the Dao Di and surrounding region, which may improve the accumulation of medicinal ingredients of populations in the Dao Di. The populations of A. bidentata were divided into two genetic groups, which was caused by five temperature variables (Bio1, Bio4, Bio7, Bio9, and Bio11). This study thus provides an important case for over-collecting within limited ranges in affecting population diversity and bioclimate variables for different producing area in driving population differentiation.     

Population genetic structure of orchid bees (Euglossini) in anthropogenically altered landscapes

Habitat degradation and fragmentation are widespread phenomena in tropical regions. Negative effects on the biota are numerous, ranging from interruption of gene flow among populations, to the loss of genetic diversity within populations, to a decline in species richness over time. Orchid bees (Hymenoptera: Apidae: Euglossini) are of major conservation interest due to their function as pollinators of numerous orchid species and other tropical plants. Here, we used microsatellite markers to investigate the effects of geographic distance and habitat fragmentation on gene flow among populations. Populations of Euglossa dilemma in three geographic regions??the Yucat??n peninsula (Mexico), Veracruz (Mexico), and Florida (USA)??were genetically structured predominantly across the regions, with the strength of differentiation among populations being positively correlated with geographic distance. Within geographic regions only little substructure was found, suggesting that dispersal is substantial in the absence of geographic or ecological barriers. In a second study, patterns of genetic differentiation among eight species of Euglossa were not related to habitat fragmentation following deforestation in southern Mexico (Veracruz). Specifically, most bee populations in the 9,800?ha forest remnant of Los Tuxtlas (Volcano San Martin) were neither differentiated from, nor had less genetic diversity than, populations in near-continuous forest separated from Los Tuxtlas by 130?km of agricultural land. Either occasional long distance dispersal across open areas has buffered the expected genetic effects of fragmentation, or the history of fragmentation in southern Mexico is too recent to have caused measurable shifts in allelic composition.     

Population genetic structure and interspecific differentiation between Acer davidii Franchi. and A. morrisonense Hayata (Aceraceae) based on SSR markers

Acer davidii Franch. and A. morrisonense Hayata are two important forest tree species (Aceraceae) endemic to mainland China and the Taiwan area, respectively. To investigate population structure and interspecific differentiation between them, we characterized a set of novel microsatellite markers using Illumina sequencing technology. The cross-species amplification analysis showed that 11 out of 21 polymorphic SSR primers of A. davidii also exhibited polymorphisms in A. morrisonense. At the species level, A. davidii has a slightly higher genetic diversity (mean observed heterozygosity, H_O = 0.180) than A. morrisonense (H_O = 0.119). AMOVA showed that most of the variations in A. davidii occurred among individuals within populations and within individuals. Bayesian clustering analyses demonstrated that the two maple species formed two clear genetic lineages. PCoA showed that A. davidii and A. morrisonense were significantly divided into two genetic groups. In addition, asymmetrical weaker gene flow was detected among the two forest tree species. These results suggest that the long term geographic isolation between the mainland and Taiwan may have resulted in a high level of genetic differentiation between these two important maple species.     

Development of EST-SSR for preliminary analysis of genetic diversity of Cordyceps militaris

Through previous research, different populations of Cordyceps militaris were determined to have varying contents of cordyceps polysaccharides and cordycepic acid, which is involved inantioxidant activity and immune stimulation. This study aimed to exploit expressed sequence tags-simple sequence repeats (EST-SSRs) and to analyse the population genetic differentiation of C. militaris. The SSR frequency of C. militaris in ESTs was 24.3%. Mono-repeats were the most abundant motif (83.4%), and the most frequent mono-repeat was A/T (98.8%). The percentage of polymorphic bands (PPB) of the seven populations of C. militaris ranged from 11.7% to 73.7% with a mean of 34.7%.Shannon's information index ranged from 0.0576 to 0.3021 with a mean of 0.1623. The total genetic diversity of C. militaris was 0.1907, and the genetic diversity within the population was 0.1049. The coefficient of gene differentiation was 0.4500, indicating extensive genetic differentiation of this species. The mean Nei's genetic distance among the C. militaris populations was 0.1184. The UPGMA dendrogram exhibited a low correlation between the genetic and geographic distances, which can also be confirmed by the Mantel test. The high level of diversification among populations may be due to deforestation and forest fragmentation in China.     

Characterization of chloroplast microsatellite loci from whole chloroplast genome of Camellia taliensis and their utilization for evaluating genetic diversity of Camellia reticulata (Theaceae)

This study characterized chloroplast microsatellite markers for Camellia reticulata, a famous ornamental and edible economic tree species only distributed in Southwestern China. Thirty-two chloroplast microsatellite markers were originally annotated in the whole chloroplast genome of Camellia taliensis, ten polymorphic microsatellite markers were tested in 96 individuals from four natural populations of C. reticulata. Alleles numbered from two to four, and average value of Shannon's Information index, Nei's gene diversity, total genetic diversity, genetic diversity within populations, gene differentiation coefficient and gene flow index were 0.408, 0.225, 0.217, 0.102, 0.530 and 0.443, respectively. Our results showed high genetic differentiation and limited gene flow among the studied populations, which may be explained by recent fragmentation of the remnant populations due to human destruction and disturbance of natural habitats of the species. The identified cpSSR markers will be useful for the future studies on population genetics, conservation biology and phylogeography of C. reticulata.     

Dendroecological and genetic insights for future management of an old-planted forest of the endangered Mediterranean fir Abies pinsapo

Pinsapo fir (Abies pinsapo Boiss.) is an endangered Mediterranean conifer that has raised strong conservation interest as a paradigmatic example of species characterized by small and fragmented populations. We studied an old reforestation stand composed of A. pinsapo, Pinus nigra and Pinus sylvestris established in the 1910s in central-eastern Spain (about 500 km north of the species native distribution range), with the aim of evaluating the stand’s suitability as an ex situ conservation unit for the fir. To this end, we investigated the long-term performance of the stand and assessed genetic diversity of A. pinsapo. Tree-ring width (TRW) and carbon isotope discrimination (Δ¹³C) were used to characterise growth dynamics and intrinsic water-use efficiency (WUE_i), respectively. Furthermore, 42 pinsapo firs were genotyped at five microsatellite loci to compare their genetic variation with published data on natural populations. A. pinsapo showed ca. two-fold higher radial growth than pines in the last 80 years; however, a growth decrease was observed for all species from the 1990s onwards. Indexed TRW was positively associated with Δ¹³C at the species level, denoting inter-annual growth dependence on water availability. Overall, Δ¹³C was higher for A. pinsapo compared to pines, indicating lower WUE_i, but Δ¹³C significantly decreased over the last 50 years for all species, likely as the result of tighter stomatal regulation of water loss, resulting in WUE_i increases of about 25 %. Recently, however, A. pinsapo showed reduced WUE_i increase in concord with growth slowdown, suggesting a threshold response for stomatal regulation. Although genetic diversity of A. pinsapo was about half of natural populations, the old-planted stand could be important for the conservation of this endemic species considering its good long-term growth and physiology. The latest decrease in performance of A. pinsapo, however, asks for urgent management measures aimed at reducing the competition for water and promoting growth and natural regeneration. This study illustrates the potential of combining tree-ring-based long-term physiological information with genetic data to ascertain the prospects of artificial stands for conservation purposes.     

Unconstrained gene flow between populations of a widespread epiphytic lichen Usnea subfloridana (Parmeliaceae,Ascomycota) in Estonia

Few studies have investigated the genetic diversity of populations of common and widespread lichenized fungi using microsatellite markers, especially the relationships between different measures of genetic diversity and environmental heterogeneity. The main aim of our study was to investigate the population genetics of a widespread and mainly clonally reproducing Usnea subfloridana at the landscape scale, focusing on the comparison of lichen populations within hemiboreal forest stands. Particular attention has been paid to the genetic differentiation of lichen populations in two geographically distinct regions in Estonia and the relationships between forest characteristics and measures of genetic diversity. We genotyped 578 Usnea thalli from eleven lichen populations using seven specific fungal microsatellite markers. Measures of genetic diversity (allelic richness, Shannon's information index, Nei's unbiased genetic diversity, clonal diversity, the number of multilocus genotypes, the number of private alleles, and the minimum number of colonization events) were calculated and compared between Usnea populations. Shared haplotypes, gene flow and AMOVA analyses suggest that unconstrained gene flow and exchange of multilocus genotypes exist between the two geographically remote regions in Estonia. Stand age, mean circumference of the host tree, size of forest site and tree species composition did not show any significant influence on allelic richness, Shannon's information index, Nei's unbiased genetic diversity, clonal diversity, the number of private alleles, and the minimum number of colonization events of U. subfloridana populations. Therefore it was concluded that other factors of habitat heterogeneity could probably have a more significant effect on population genetics of U. subfloridana populations.     

Weak genetic structuring indicates ongoing gene flow across White-ruffed Manakin (<Emphasis Type="Italic">Corapipo altera</Emphasis>) populations in a highly fragmented Costa Rica landscape

We explored the effects of recent forest fragmentation on fine-scale patterns of population structuring and genetic diversity in populations of White-ruffed Manakins (Corapipo altera) inhabiting premontane forest fragments of varying size in southwestern Costa Rica. Habitat fragmentation is a major conservation concern for avian populations worldwide, but studies of the genetic effects of fragmentation on Neotropical birds are limited. We sampled 159 manakins from nine forest fragments of varying size within an 18 km radius, and genotyped these birds at 13 microsatellite loci. Bayesian clustering methods revealed that birds from all fragments comprised a single genetic population, and an MCMC approach showed that the fragments were likely to be at migration-drift equilibrium. F-statistics showed only modest levels of differentiation between forest fragments. We calculated allelic diversity indices for each fragment but found no correlation between genetic diversity and fragment size. These results suggest that manakins may retain substantial connectivity via inter-fragment dispersal despite habitat fragmentation.     

Study on reproduction ecology of endangered species Abies chensiensis

Qinling fir, Abies chensiensis, is endemic to China and has been listed in the China Plant Red Data Book as one of the second class conservation plants. It is found scattered only in the forested pockets of the Qinling, Bashan, and Shennongjia Mountains with altitude from 1 300 m to 2200 m in Shaanxi, Gansu, Henan, Sichuan, and Hubei Provinces. To conserve and effectively restore this species and explore its processes of reproduction, the production characteristics of cone and seed yields, seed bank dynamics, and seed germination rates of five Abies chensiensis populations (A, B, C, D, and E, respectively, in the Abies chensiensis-Pinus tabulaeformis-Sinarundinaria nitida-Carex lanceolata association, Abies chensiensis-Quercus aliena var. acutserrata-Litsea pungens-Carex lanceolata association, Abies chensiensis-Betula albo-sinensis-Sinarundinaria nitida-Duchesnea indica association, Abies chensiensis-Indigofera amblyantha-Carex lanceolata association and Abies chensiensis-Pinus tabulaeformis-Smilax stans-Carex lanceolata association) were studied in their natural habitats across 18 plots in the Qinling Mountain area. Experiments were carried out in laboratory and field conditions. The results showed that all the five populations had the potential to produce seeds, and higher yields occurred in the lower and middle altitude areas every three to five years. The majority of cones appeared on the upper and middle crown and the west, south, and east faces of the crown, and the majority of full seed appeared on the middle portion of the cone. The weight per 1000 seeds was 43.2 g, in which 44.8% had growing potential. The germination rate of seeds in the natural forest was 6.1% and the proportion of seeds lost or destroyed in different populations in the natural forest was 93.9%. The germination rate of seeds planted in the nursery was higher than that in the natural forest, and the germination rate in the lower or middle altitude populations was higher than that in the upper altitude populations. The course from seed to seedling was the critical period in the life cycle of A. chensiensis populations under natural conditions. Reproduction courses were influenced positively by an abundant coverage of tree layer, organic material in the soil, thick soil, and a dense population of parent trees, whereas they were influenced negatively by human disturbance and light. In situ conservation of A. chensiensis should be carried out in the future so as to promote expansion of the population. Thinning the shrub layer and grass layer will also help seeds to penetrate the soil, promoting seed germination. The artificial population should be expanded by collecting seeds in the harvest years. Fast-growing and high-yield plantations should be developed on cloudy slopes at lower or middle altitudes.     

Phylogeography and genetic structure of disjunct Salix arbutifolia populations in Japan

Disjunct geographic distributions of boreal plant species at the southern edges of their ranges are expected to result in low genetic diversity and high genetic differentiation in the disjunct populations. This prediction was tested in a riparian willow, Salix arbutifolia, distributed in the northeastern Eurasian continent and the Sakhalin, Hokkaido, and Honshu Islands, using chloroplast DNA haplotypes and nuclear microsatellite genotypes. Hokkaido and Honshu populations shared a chloroplast haplotype identical to a closely related species, S. cardiophylla. This haplotype was divergent from haplotypes in the Eurasian continent (Primorsky) and the Sakhalin Island. In the nuclear microsatellites, most Hokkaido populations were genetically closer to Primorsky populations than to Sakhalin populations in spite of the geographical vicinity between Sakhalin and Hokkaido. The unexpected genetic divergence between Sakhalin and Hokkaido implies a complicated history of migration and colonization. The most peripheral populations in Honshu had the lowest genetic diversity and were most differentiated from the others. Thus, low genetic diversity and high genetic differentiation at the range periphery suggest substantial effects of genetic drift on genetic structure in the disjunct populations of Salix arbutifolia at the southern edge of its range.     

Assessment of genetic diversity and chemical composition among seven black locust populations from Northern China

Black locust (Robinia pseudoacacia L.) is one of the important biomass sources used to produce bioenergy and bioethanol. In this study, we examined variations in chemical composition as well as genetic diversity and differentiation among 165 black locust plants from seven populations in five provinces (Beijing, Hebei, Gansu, Shanxi, Shandong) of Northern China using microsatellite markers(SSR). The contents of cellulose, hemicellulose, lignin varied widely among seven populations. Of the microsatellite markers analysed, 14 showed polymorphisms, and 45 alleles were identified. The polymorphism information content (PIC) ranged from 0.2885 (Rops4) to 0.6837 (Rp200), and most of the microsatellite loci had PIC values > 0.5. Expected heterozygosity (He), observed heterozygosity (Ho), and Shannon's information index (I) detected relatively high genetic variation among populations. The percentage of polymorphic loci in three populations was 100%, and the average among all populations were 95.92%. Analysis of molecular variance (AMOVA) indicated that the degree of genetic differentiation among the seven populations was low (G_ST = 0.058; N_m = 4.05), and chemical compositions had no relationship with genetic or geographic distance. This study demonstrates that microsatellite markers efficiently assess of genetic diversity and genetic differentiation in black locust populations, and all seven populations exhibit high genetic diversity. The population from Feixian has the potential to be lingo-cellulosic biomass for bioenergy and bioethanol.     

High genetic diversity in fragmented Iris pumila L. populations in Ukrainian steppe enclaves

Habitat fragmentation can prevent gene flow between plant populations and lead to a loss of genetic diversity. However, such impact of fragmentation has not always been consistently confirmed by previous studies and the issue still needs further research. Particularly little is known about the impact of fragmentation on steppe plants. Steppe once covered vast, continuous areas, and nowadays is among the most fragmented biomes. In Ukraine, remnants of this habitat survived in large but few nature reserves and loess ravines as well as on kurgans (burial mounds of ancient nomadic people), which, despite their small size, are still numerous and scattered throughout the landscape.We studied the impact of fragmentation on the genetic diversity and structure of Iris pumila, a typical species of European steppes. Our main focus was to compare the genetic characteristics between kurgan populations (n = 8), and populations from larger refugia (n = 6). We assessed the genetic diversity of the studied populations with Universal Rice Primers.Our analyses revealed high genetic diversity across all investigated populations (mean He: 0.233; mean PPB: 58.57). However in kurgan populations genetic diversity was significantly higher than in larger refugia. Genetic diversity (He) was negatively correlated with population size. Most of the molecular variance (82%) was represented within populations, whereas genetic differentiation among populations was moderate (Φ_ST = 0.160), and low among refugia types (Φ_RT = 0.026).The maintenance of high genetic diversity despite two centuries of fragmentation may be related to the moderate disturbance occurring on kurgans, which enhances the sexual reproduction of the species. Moreover, we assume that species traits such as longevity and polyploidy might counterbalance genetic drift, while its self-incompatibility and presence of a soil seed bank allows for the replenishment of the gene pool. Overall, our results suggest that kurgans can protect genetic diversity of steppe species.     

Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae)

Given predicted rapid climate change, an understanding of how environmental factors affect genetic diversity in natural populations is important. Future selection pressures are inherently unpredictable, so forest management policies should maintain both overall diversity and identify genetic markers associated with the environmental factors expected to change most rapidly, like temperature and rainfall. In this study, we genotyped 648 individuals in 28 populations of Castanopsis fargesii (Fagaceae) using 32 expressed sequence tag (EST)-derived microsatellite markers. After removing six loci that departed from Hardy–Weinberg equilibrium, we measured genetic variation, population structure and identified candidate loci putatively under selection by temperature and precipitation. We found that C. fargesii populations possessed high genetic diversity and moderate differentiation among them, indicating predominant outcrossing and few restrictions to gene flow. These patterns reduce the possible impact of stochastic effects or the influence of genetic isolation. Clear footprints of divergent selection at four loci were discovered. Frequencies of five alleles at these loci were strongly correlated with environmental factors, particularly extremes in precipitation. These alleles varied from being near fixation at one end of the gradient to being completely absent at the other. Our study species is an important forest tree in the subtropical regions of China and could have a major role in future management and reforestation plans. Our results demonstrate that the gene flow is widespread and abundant in natural populations, maintaining high diversity, while diversifying selection is acting on specific genomic regions.     

Limited genetic differentiation in Labeo rohita (Hamilton 1822) populations as revealed by microsatellite markers

Labeo rohita, popularly known as rohu is a widely cultured species in the whole Indian subcontinent. Knowledge of the genetic diversity of this species is important to support management and conservation programs which will subsequently help in sustainable production of this species. DNA markers, mostly microsatellite markers are excellent tool to evaluate genetic variation of populations. Genetic variation of three wild and one farm population was assessed using eleven microsatellite loci. In analyzing 192 samples, the number of alleles ranged from 4 to 23; observed heterozygosity 0.500 to 0.870 and expected heterozygosity from 0.389 to 0.878. Exact test for Hardy Weinberg disequilibrium revealed that each riverine sample had at least one locus not in equilibrium except one river. Negative inbreeding coefficients (F_IS) were observed across populations indicating very high level of genetic diversity but little genetic differentiation among populations.     

Post‐glacial history and introgression in Abies (Pinaceae) species of the Russian Far East inferred from both nuclear and cytoplasmic markers

Aim The main aim of the present study is to infer the post‐glacial history of Abies species from north‐east Asia and to test the hypotheses that coastal Abies populations suffered less from climatic fluctuations during Pleistocene glacial periods than their more continental counterparts, and that Sakhalin was a major area of introgression. Location Natural ranges of the fir species Abies nephrolepis, Abies sachalinensis and Abies holophylla in the Russian Far East, and of Abies gracilis, which is endemic to the Kamchatka Peninsula. Methods Nineteen populations were sampled for allozyme analysis. Seventeen of these populations were also screened for variation at two paternally inherited chloroplast DNA microsatellite loci (cpSSR) and variation at one maternally inherited mitochondrial marker (nad4‐3/4). Finally a subset of 11 populations was analysed with amplified fragment length polymorphism (AFLP). Comparisons were made with already available Abies sibirica data. For all sets of markers, we estimated genetic diversity and differentiation using an analysis of molecular variance (AMOVA). Population clustering was assessed with a Bayesian approach implemented in structure v.2.3. Results Among the three major species, A. sibirica, A. nephrolepis and A. sachalinensis, A. sachalinensis demonstrated the highest cytoplasmic and nuclear diversity and the most continental species, A. sibirica, the lowest. Both nuclear and mitochondrial DNA markers revealed the presence of a transitional zone on Sakhalin Island between A. nephrolepis and A. sachalinensis of south Sakhalin. The structure analysis delivered very clear results confirming the admixed origin of A. sachalinensis, with a genetic contribution from A. nephrolepis. No variation in cytoplasmic markers was found in A. gracilis, suggesting the occurrence of a recent bottleneck. Main conclusions There is a clear reduction of genetic diversity in Abies species from the Pacific coast into the continent. The higher diversity in A. sachalinensis could have two causes: a larger effective population size in the islands due to relatively stable climatic conditions and consequently less pronounced demographic fluctuations in population size and/or hybridization with continental and Japanese populations. Sakhalin Island is a major transitional zone for conifer species. Finally, the fir from Kamchatka, A. gracilis, should be regarded as a separate species closely related to the A. nephrolepis–A. sachalinensis complex.